Lockable cylinder piston units are used e.g. in chair columns carrying a seat member for height adjustment of the seat member. They can also be used for positioning a back rest of a chair or the like. Moreover, they can be used for many industrial and household appliances where objects are to be positioned in various positions. There exists frequently the problem to provide a remote control of the locking system, e.g. in chairs the cylinder piston units for positioning the seat or the back rest should easily be controllable by the user of the chair when sitting on the chair.